Chrome on mobile absolutely has a text zoom, it's exposed as an OS function, but chrome respects it... my vision is not great, so in accessibility settings I have fonts set to largest. Chrome does a decent job (as most Android UI) of respecting this. The apps that don't, or don't do it well (Facebook) are the ones that are particularly annoying.
It may not be exposed in the browser directly, but the functionality is definitely there.
edit: and I'm frankly okay with using px/pt for the baseline font at the root level and using em/rem elsewhere. In the end, I understand that it should be 72pt/in and 96px/in as far as CSS goes... others may not... Devices that don't have their actual PPI set so browsers can properly calculate the CSS dimensions is slightly annoying though. But that's been a bit craptastic forever and a day.
In the end, nothing will ever be close to perfect. I do find it annoying that different fonts with the same size and line-height will render far differently... a 12pt font should render (roughly) 6 lines per inch.
It may not be exposed in the browser directly, but the functionality is definitely there.
edit: and I'm frankly okay with using px/pt for the baseline font at the root level and using em/rem elsewhere. In the end, I understand that it should be 72pt/in and 96px/in as far as CSS goes... others may not... Devices that don't have their actual PPI set so browsers can properly calculate the CSS dimensions is slightly annoying though. But that's been a bit craptastic forever and a day.
In the end, nothing will ever be close to perfect. I do find it annoying that different fonts with the same size and line-height will render far differently... a 12pt font should render (roughly) 6 lines per inch.